Find the resistance of the wire figure shown in Fig. 26.2a. The wire is uniform, made of aluminium of 0.4 mm diameter. The length of the side of the square is 20 cm.

Answer

26 mohm

Explanation

From the symmetry of the circuit it is evident that the potentials of points 2 and 4 are equal, so no current flows through the conductor 2-4 and it may be removed. This gives the circuit of Fig 26.2b whose resistance is easily found.